Manufacturers of disk drives are requiring higher storage capacity. Disk drives used in portable computers must be able to withstand the shocks encountered during handling and travel. Monolithic ferrite heads, though less costly than composite heads, do not exhibit sufficient shock resistance. Thin film heads have several desirable attributes. They do not require winding, machining and assembly--all labor intensive tasks required in ferrite head manufacturing. However, thin film heads are more costly to manufacture than composite heads.
Composite ceramic-ferrite heads are very rugged since the magnetic core is glass bonded to a strong ceramic slider. Though more expensive then monolithic heads, composite heads have a potential of higher track density. Moreover, since the magnetic core can be formed with parallel sides, composite heads have a more focused magnetic flux field for writing.
However, composite heads containing single crystal ferrite (SCF) cores exhibit a readback oscillation when a write current is shut off, and the head is placed in a read mode. The readback oscillation interferes with the read operation until it is dampened. This can take 15-20 micro seconds depending on the severity of the oscillation and can also cause servo errors in the drive.